Normally a class-D amplifier comprises an output stage consisting of two n-type power MOSFETs in a totempole configuration as shown in FIG. 1. The output node Vout is switched between the supply lines using some form of pulse-width modulation (PWM). An LC-lowpass filter is usually inserted between the output node Vout and the loudspeaker load to filter out the high frequency content. A driver circuit that is supplied from a regulated source Vreg controls the gate of the lowside power MOSFET ML. This topology automatically limits the gate-source voltage of the power MOSFET. Another driver circuit controls the gate of the highside power MOSFET MH. In order to switch ON the highside power MOSFET MH a gate voltage higher than the supply voltage Vdd is needed. This voltage is created dynamically using a bootstrap capacitor Cboot. When the lowside power MOSFET ML is switched ON the output node Vout is pulled down to the negative supply Vss. The bootstrap capacitor Cboot is charged through a bootstrap diode Dboot connected between the regulated source Vreg and a bootstrap voltage Vboot. When the highside power MOSFET MH is switched ON and the lowside is switched OFF, the output node Vout is pulled up to the positive supply Vdd. Now the bootstrap diode Dboot becomes reverse biased and the bootstrap capacitor Cboot serves as a floating power supply for the highside driver. Usually, the highside driver has a moderate current consumption causing the voltage across the bootstrap capacitor Cboot to decrease. However, each time the class-D power stage switches the bootstrap capacitor Cboot is recharged. A disadvantage of the bootstrap configuration is that the voltage across the bootstrap capacitor Cboot is always lower than the voltage of the regulated source Vreg because of the inevitable voltage drop across the bootstrap diode Dboot. This voltage is typically 0.6V at room temperature but can increase to almost 1V at −40° C. A lower bootstrap voltage means less gate-source voltage for the highside power MOSFET MH and thus a higher Ron. Further, for optimal operation of a class-D power stage as shown in FIG. 1 it is desirable that the bootstrap voltage matches the voltage of the regulated source.